1. Field of the Invention
The present invention pertains to a plasma display panel (PDP), and in particular, to a design for a PDP design that results in improved bright room contrast while maintaining a high opening ratio and a high luminance.
2. Description of the Related Art
In general, a PDP is a display device where ultraviolet rays generated during gas discharge excite phosphors to produce a visible image. PDPs have received a lot of attention recently as next generation display devices because of their large screen size, thin depth, and high resolution.
PDPs are classified into direct current (DC) types and alternating current (AC) types based on the driving power. One type of AC PDP that has become very popular recently is the three-electrode type AC PDP that has an address electrode and a pair of display electrodes.
PDPs can be further classified according to the layout of the discharge cells where an independent discharge takes place. For example, the PDP can be classified as a stripe-type (or in-line type), where three red (R), green (G), blue (B) discharge cells are arranged in a stripe pattern, or a delta-type where discharge cells have a triangular shape.
In both the stripe-type and delta-type PDPs, address electrode, barrier ribs, and a phosphor layers are formed on the rear substrate and correspond to each discharge cell bounded by the barrier ribs, and display electrodes that include of scan electrodes and sustain electrodes are formed on the front substrate. A dielectric layer is formed on the rear substrate and on the front substrate to cover the display electrodes and the address electrodes. A discharge gas, being a Ne—Xe gas mixture, fills the discharge cells at locations where the address electrodes cross the display electrodes.
A discharge cell for light emission is selected by an address discharge that occurs when an address voltage is applied between the address electrode and the scan electrode. Then, a plasma discharge takes place inside selected discharge cells by applying a sustain voltage between the sustain electrode and the scan electrode, generating a plasma that emits vacuum ultraviolet rays that excites the phosphor layer in the discharge cell to emit visible light to form an image.
In an AC PDP, the sustain electrodes and the scan electrodes are made of a transparent material, such as indium-tin oxide (ITO), so that visible rays can be transmitted through them. The poor conductance of the transparent material is compensated by an additional bus electrode that is made of a highly conductive and opaque metal and is located outside the discharge area.
As described above, a higher opening ratio can be achieved by having the scan and the sustain electrodes made of a transparent material and also by having bus electrodes located outside the discharge area. However, such a design results in poor bright room contrast of the PDP operating under in bright room conditions because of a low absorption efficiency of outside light. Therefore, what is needed is a design for an AC PDP that provides for improved bright room contrast while also having a high opening ratio and high luminance characteristics.